August 20, 2013

Comet Activity Starting Up Early Ahead Of 2014 Rosetta Mission

Comet Churyumov-Gerasimenko, a 2014 visitor to our neck of the woods, will be emitting gas and dust earlier than expected, according to a new study by the Max Planck Institute for Solar System Research (MPS).

The European Space Agency's (ESA) Rosetta spacecraft will be arriving at comet Churyumov-Gerasimenko next year, and two months after it starts its approach, the comet will start showing activity. Researchers say the comet's activity will be measurable from Earth by March 2014.

Scientists, publishing a paper in the journal Astronomy & Astrophysics, wrote that they analyzed numerous images from the comet's past three orbits around the Sun and they were able to reconstruct the comet's activity in all phases of its orbit for the first time.

Comets spend most of their life far from the Sun as an unchanged lump of ice and rock, but as it approaches closer to our local star a reaction begins to take place. Highly volatile substances vaporize from the nucleus carrying fountains of dust particles with them. These accumulate to form the comet's atmosphere, which is the origin of its tail.

Rosetta will be attempting to answer some remaining questions about comets when it rendezvous with comet Churyumov-Gerasimenko in the spring. The spacecraft will be placing a lander on the comet's surface in the autumn of 2014, which will accompany the comet as it makes its way toward the Sun. This mission will offer scientists a unique chance to study all phases of the onset of comet activity from close-up.

"Churyumov-Gerasimenko could be active by March of next year," said Dr. Colin Snodgrass from the MPS. "We were able to analyze data from the entire activity-cycle of Churyumov-Gerasimenko with the same method. For the first time, this allows for a meaningful comparison of all data sets."

Dr. Cecilia Tubiana from the MPS said that they were able to compile a comprehensive picture of how the comet's activity develops during its journey around the Sun. The team based their predictions on 31 data sets recorded between 1995 and 2010 with telescopes like the European Southern Observatory's Very Large Telescope (VLT).

"Most of the images taken in 2007, when the comet was far away from the Sun, present a significant difficulty," says Tubiana.

In 2007, the comet could be seen from Earth only in front of the background of the Galactic center, which is the mass center of the Milky Way. Next year, when Rosetta arrives at the comet, the observational situation will be similar.

Rosetta launched in 2004 and is scheduled to reach the comet in 2014. The space probe will be releasing the lander Philae on the comet's surface in the fall of 2014.

Rosetta will be busy gathering data around the comet with its onboard sensors. The space probe will be mapping the comet's surface and magnetic field, monitoring Churyumov-Gerasimenko's erupting jets and geysers, and measuring outflow rates. The mission will build a 3D picture of the layers and pockets under the surface of a comet.

In 2008 Rosetta passed within 500 miles of asteroid Steins, allowing ESA to capture images of the rare E-type asteroid.

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Image Below: In the course of one orbit around the Sun, the comet Churyumov-Gerasimenko goes through different phases of activity. At a distance of 3.4 astronomical units (AU) a significant increase in brightness can be observed. Shortly before crossing the orbit of Mars the comet has developed it characteristic tail. Departing from the Sun, Churyumov-Gerasimenko is still very active and shows a dust trail, a structure composed of large dust particles emitted during the previous orbits of the comet. This trail can still be discerned at a distances of 4.9 astronomical units from the Sun. Credit: MPS